An attenuated Mycobacterium bovis RD1 deletion (ΔRD1) mutant of the Ravenel strain was constructed, characterized, and sequenced. This M. bovis ΔRD1 vaccine strain administered to calves at two weeks of age provided similar efficacy as M. bovis bacillus Calmette Guerin (BCG) against low dose, aerosol challenge with virulent M. bovis at 3.5 months of age. Approximately 4.5 months after challenge, both ΔRD1-and BCG-vaccinates had reduced tuberculosis (TB)-associated pathology in lungs and lung-associated lymph nodes and M. bovis colonization of tracheobronchial lymph nodes as compared to non-vaccinates. Mean central memory responses elicited by either ΔRD1 or BCG prior to challenge correlated with reduced pathology and bacterial colonization. Neither ΔRD1 or BCG elicited IFN-γ responses to rESAT-6:CFP-10 prior to challenge, an emerging tool for modern TB surveillance programs. The ΔRD1 strain may prove useful for bovine TB vaccine programs, particularly if additional mutations are included to improve safety and immunogenicity.
-Inoculation of vesicular stomatitis New Jersey virus (VSNJV) by skin scarification of the coronary-band in cattle, a natural host of VSNJV, resulted in vesicular lesions and 6−8 log 10 TCID 50 increase in skin virus titers over a 72 h period. Virus infection was restricted to the lesion sites and lymph nodes draining those areas but no virus or viral RNA was found in the blood or in 20 other organs and tissues sampled at necropsy. Scarification of flank skin did not result in lesions or a significant increase in viral titer indicating that viral clinical infection is restricted to skin inoculation at sites where lesions naturally occur. Viral antigens co-localized primarily with keratinocytes in the coronary band, suggesting these cells are the primary site of viral replication. Viral antigen also co-localized with few MHC-II positive cells, but no co-localization was observed in cells positive for macrophage markers. Although granulocyte infiltration was observed in lesions, little viral antigen co-localized with these cells. This is the first detailed description of VSNJV tissue distribution and infected cell characterization in a natural host. The pathogenesis model shown herein could be useful for in-vivo tracking of virus infection and local immune responses. vesicular stomatitis / bovine / pathogenesis / confocal microscopy / keratinocytes
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